Hardware add-on fits right on top of the ultra-cheap computer, costs $14 for 3.

Joe Walnes, a Chicago-based hacker and maker, has just released a design for what he has dubbed the Pi Crust: a very cheap new hardware add-on for the Raspberry Pi.

The breakout board, which debuted on Wednesday, is meant to make it easier to tack various hardware peripherals onto the cheap computer, and it does so in an compact design. The new board only adds 2mm of height to the existing Raspberry Pi.

As Walnes lays out on his site, there are various well-labelled pins, including GPIO, I2C, SPI, UART, and power.

"This makes it so you can connect things directly to a Raspberry Pi. The Raspberry Pi has the capability to do all this stuff, but it’s a bit inconvenient," Walnes told Ars. "[The Pi Crust] just makes it a little bit simpler. It’s nothing revolutionary, it’s just taking the pins on the RP and laying them out to make them more convenient to access and it’s nice and compact."

Expanding access to the Raspberry Pi's General Purpose Input/Output (GPIO) pins is probably one of the most important aspects of this add-on—Arduinos, for example, use GPIOs to read from various environmental sensors.

"The Raspberry Pi can communicate or control other circuits that are attached to this connector," said Malcolm Knapp, a Berkeley-based electrical engineer who has helped Ars on various DIY projects.

"However all the different signals are grouped together, which makes them hard to connect to. So the Pi Crust separates them out into groups and labels each group so it is easier to connect to them."

Walnes isn’t selling the Pi Crust; he's just making the design specification available. He links to a circuit board printing shop where he says customers could have three of them printed for less than $14.

"I suspect that someone will start selling these, and someone will start buying a bulk of these and selling them a lot cheaper," he added.